NEW BRUNSWICK, N.J. — Sen. Robert Menendez is suddenly big news in Washington. The new chairman of the Senate Foreign Relations Committee is at the center of a bipartisan group working to overhaul the nation’s immigration laws and the focus of a brewing political scandal.

But neither success nor scandal is new to Menendez (D), so back home in New Jersey the reaction to his ups and downs is decidedly more muted than inside the Beltway.

“People have been making allegations against Bob Menendez since he was on the school board. Time and again it’s been proven untrue,” said Mercer County Executive Brian Hughes (D), a longtime party activist in New Jersey.

Menendez faces a Senate Ethics Committee investigation into free trips he took to the home of a major campaign donor in the Dominican Republic. (He has since repaid $58,500 for the costs of two round-trip flights on a private jet.) Conservative news outlets also accuse Menendez of having sex with underage prostitutes, a charge he strongly denies.

And New Jersey Democrats are paying little attention to the probe. They are more focused on Gov. Chris Christie, their high-profile GOP nemesis, who is up for reelection this year and is often mentioned as a 2016 White House contender. Christie enjoys a 74 percent approval rating, according to a recent poll.

Before his rise to national GOP stardom, Christie was a political cult hero in New Jersey for his tough-on-corruption prosecutions as U.S. attorney during George W. Bush’s presidency. One case involved a high-profile probe into Menendez that became public in October 2006, just before the senator’s heated election against Thomas Kean Jr., the son of New Jersey’s popular former governor and a close ally of Christie’s. The case centered around allegations that Menendez steered federal funds to a nonprofit group run by a friend, with the organization then renting space in a building Menendez owned.

The investigation produced no charges, and Menendez won by nearly 10 percentage points. State Republicans consider it the moment Menendez dodged an ethical bullet, but Democrats point to the probe as an example of Christie’s overly aggressive prosecutorial nature.

Hundreds of those Democrats gathered Saturday for a rally in the New Brunswick High School gymnasium to launch the gubernatorial campaign of state Sen. Barbara Buono, their nominee to challenge Christie. The 59-year-old is the daughter of an Italian immigrant butcher, and her stump speech struck a populist tone by promising economic renewal. Buono told supporters that under Christie, the middle class has “gotten nothing — nothing — but sound bites and empty promises from a governor who seems more intent on courting his right-wing base than tending to the needs of the middle class and working poor.”

Christie spokesman Mike DuHaime dismissed Buono as “part of the problem of high taxes, runaway spending and irresponsible debt for nearly 20 years in Trenton.” As for Menendez, Christie told reporters last week that it would be “inappropriate” to opine on the accusations.

New Jersey lacks a major in-state media market — most residents rely on television and radio stations in New York and Philadelphia for their news and weather — so politicians earn statewide recognition by word of mouth. It is a strategy that relies heavily on myriad local, county and state political bosses and makes the state’s politics “incredibly inward-looking,” said Ross K. Baker, a Rutgers University professor of U.S. politics and longtime state political observer.

The result is that the face-off with Christie is far bigger news than Menendez’s D.C. travails.

“Washington seems like a very distant place here, even though it’s just 200 miles away,” Baker said. “Most of the attention here focuses on state issues, because people here seem to think that the stakes at the state level are higher.”

During his rise to the Senate, Menendez built similar support among party bosses from his home base of Hudson County, which sits directly across the Hudson River from New York. As a college student in the early 1970s, Menendez won a school board seat. He later became mayor of Union City, then moved to Trenton as a state lawmaker before winning a House seat in 1992. In Washington, he was chairman of the House Democratic Caucus before jumping to the Senate, where he led the Democratic Senatorial Campaign Committee during the 2010 midterm cycle.

Hudson County Democratic Party Chairman Mark Smith said Saturday that he last saw Menendez a few weeks ago when the senator visited Bayonne, N.J., to announce new federal funding for local projects.

“Right now he’s got a track record of service to the people,” Smith said. “Right now he faces accusations — but it’s just that, accusations. Let’s see how it plays out.”

If the allegations prove true, Menendez could be forced to make a quick exit from politics. The state’s long history of political corruption has left voters increasingly intolerant of leaders caught up in scandal.

Milly Brown, 82, has worked on Democratic campaigns in the state for 50 years and met Menendez during his first campaign for Congress in 1992.

“He had a hard-enough time getting to where he is,” Brown said. “Why would he take two nights of pleasure to ruin it all?” But if the accusations turn out to be true, “I’ll go up and smack his face,” she said.

In the past dozen years, a slew of top officials in New Jersey have landed in ethical quandaries that ended their careers. Former Newark Mayor Sharpe James was sentenced to prison in 2008 for selling city property to donors in cut-rate deals, a scandal that helped lift the current mayor, Cory Booker, to city hall.

In 2002, Sen. Robert G. Torricelli (D) abandoned his reelection bid after being “severely admonished” by the Senate Ethics Committee in a gifts-for-favors case related to a donor, imploding any support he had left.

Back in 2001, the acting governor, Donald DiFrancesco(R), abandoned his election bid after reports of questionable business dealings. And in 2004, Gov. James McGreevey (D) resigned as he disclosed that he was gay and acknowledged that he had placed his lover in a sensitive security position for which he was unqualified.

McGreevey, once a close political ally of Menendez, used to walk the streets of North Jersey towns visiting constituents with the senator, and on Saturday he remained supportive.

“I have the highest regard for the intellect and tenacity of Senator Menendez,” McGreevey said in an e-mail. “He is an indefatigable advocate for the voiceless in our society. These accusations too shall pass.”